Question

For a monatomic ion, the net charge on the atom is its valency.
A) True
B) False

Answer 1

Hint: A monatomic ion contains only one atom. Such an ion has either positive or negative charge. This ion is formed when a neutral atom either gains or loses electrons.

Complete answer:
To complete octet an atom requires a certain number of valence electrons. This number is the valency of that atom. For example, when sodium atom (atomic number 11) loses its only valence electron, the sodium cation is formed with stable noble gas electron configuration of neon in which octet is complete for the second energy level. Since a sodium atom loses one valence electron to complete its octet, the valence of sodium is one.

The net charge on sodium cation is +1. The valence of sodium atoms is one. Thus, you can say that the net charge on an atom in a mono-positive ion is equal to its valence. To gain stability, the number of electrons gained or lost is equal to that required for attaining a stable electronic configuration. When a certain number of electrons are gained or lost, the atom gains a net charge. This net charge is also equal to the valence of an atom in a monatomic ion. Thus, for a monatomic ion, the net charge on the atom is its valency. Hence, the given statement is a true statement.

Hence the correct answer is option ‘A’ i.e. True

Note:
i) When an atom gains one or more electrons, the monatomic ion has negative charge on it.
ii) When an atom loses one or more electrons, the monatomic ion has positive charge on it.
iii) For a metal, the valence is equal to the number of valence electrons present in a neutral atom.
iv) For a non-metal, the valence is equal to eight minus the number of valence electrons present in a neutral atom.